The use of various bio-based materials for construction is currently growing, such as natural fibers derived from wood, wheat, jute, flax, bamboo, straw, coir, etc, and the dispersion of vegetal elements (wood, hemp, cellulose wadding, straw, etc) in a mineral matrix (lime, cement, earth). This is due to their low (natural) production cost, to their ability to improve air quality and therefore to bring more comfort to the occupants thanks to their moisture-buffering effect. They also require less energy for heating or cooling, and they are partially or fully recyclable. Consequently, predicting water and heat transfers in such materials is essential to select them appropriately, adjust their conditions of use, or to devise innovative materials. Reliable modelling has to take into account the critical role of absorbed (bound) water transfers in the solid structure, coupled with heat transfers.This course presents basic tools for evaluating the hygrothermal properties of such materials. At the end of the module, students will be able to distinguish the main physico-chemical characteristics of the different types of bio-based materials for construction; they will be able to make basic calculations of heat and water transfers in such materials, and estimate the impact on the comfort and energy consumption.